I disagree with you about the Jetpack; I think it has the perfect balance of mobility versus exposure. On the other hand I agree with what you said about Forerrunner Vision. It could work, maybe, but they need to treat it very carefully, and pay close attention to map design. Beyond that, universal sprint seems like it would mess up the balance of the other AA's, but it may be negligible. We'd have to wait until we get gameplay footage to see how it goes.
Loadouts, on the other hand, are rather problematic. See, they could work, if it was just AA's, weapons, and grenades. You could choose your preferred of each, and as long as each of the weapons had a weakness (you mentioned the range differences of the DMR and BR), and there were no power weapons, it would work out. You pick the one you're best with and play to your style. It adds a layer of tactics. The only problems are the fact that there are "modifications" in there too, and that all of this stuff needs to be unlocked through rank. It could balance out if you were allowed to pick your setup from the start, but obviously if you have a limited selection of weapons, AA's, and modifications, while an opponent has a wide variety, you're at a disadvantage. Of everything we've heard, this is by far the most game-breaking, and the only way I see it not tripping over its own deformed feet and snapping its neck is if they remove the system of "higher rank means you win" entirely. Which, who knows, they may very well do, if the fan outcry is great enough.
On the other hand, the more story-driven campaign and Spartan Ops sounds incredible. Even if multiplayer fumbles and dies horribly, the game will be worth getting for single player alone.
So, I guess the best phrase so sum up my feelings on the news we've heard so far (regarding multiplayer) is "we'll see".
EDIT: Forgot about random weapons spawns and instant respawn. My thoughts on that can be summed up as follows: "Haha, seriously? No." Although, they got rid of Armor Lock, so I guess it balances out and we're back to "we'll see".